1. Field of the Invention
The present invention relates to an image processing device and an image processing control method used in a single device such as a digital copier, a fax machine, a printer or the like, or in a multifunction peripheral (MFP) that combines part or all of the processing functions of the foregoing and/or of a scanner or the like, or in other image data processing devices.
2. Description of the Background Art
Image processing devices such as digital copiers or the like require processing functions, for instance, interline correction, shading correction, MTF (spatial frequency characteristic) filtering, gamma conversion, gradation processing and the like. A multifunction device (MFP) must combine in a single unit a copier function, a scanner function, a fax function, a printer function and the like.
Among conventional image processing devices, Japanese Patent Application Laid-open No. H08-274986 and U.S. Pat. No. 5,715,070, for instance, disclose the use of data processing hardware (ASIC) having ordinarily a plurality of independent dedicated processing units, to realize thereby plural processing functions. Using data processing hardware (ASIC) having a plurality of independent dedicated processing units is advantageous on account of the superior speed performance achieved thereby, but, on the other hand, is problematic because of lack in flexibility as regards functional modifications and/or additions, on account of hardware logic. Programmable devices such as DSPs (digital signal processors) are often used as a solution to this problem. Using a programmable device such as a DSP is advantageous in that process functions can be modified/supplemented flexibly by re-downloading the process programs to the DSP. On account of software processing, however, programmable devices are by contrast inferior to dedicated hardware logic as regards speed characteristics. Conventional programmable devices are also costly since each process requires a process program memory and data memory.
Both image processing devices using ASICs and image processing devices using DSPs have thus merits and demerits, so that ordinarily either kind is used depending on the circumstances.
Meanwhile, process flows in multifunction devices (MFP) have become more diverse and complex in recent years owing to the bolstering of copier functions, scanner functions, fax functions, printer functions and the like. A number of processing functions must thus be implemented in order to meet the diverse needs of the user. The user has also a strong demand for image quality, and hence the image processing burden tends to increase in order to cope with such high-quality image requirements. The diversification and growing complexity of process flows are not only restricted to multifunction devices, but affect equally single devices such as digital copiers, fax machines, printers and other image data processing devices.
Thus, hardware components for carrying out actual image processing, typified by ASICs, are problematic on account of their increasing size and associated higher manufacturing costs. In data processing hardware such as ASICs, in particular, process-dedicated programs and process-dedicated memories must be arranged plurally in the hardware, as described above, and hence it is difficult to realize cost cuts while preserving required process functionalities. Since process functions are realized herein through an internal hardware logic provided beforehand, such data processing hardware suffers from a fundamental drawback of being lacking in flexibility as regards functional updates and/or additions.
The biggest advantage of programmable devices such as DSPs or the like is that, although inferior to ASICs, for instance, in terms of speed characteristics and/or cost, they afford a high degree of freedom as regards programming of functions in accordance with the needs of the user, at all times. That is, process changes and/or additions can be easily implemented by programming functions to be processed, and by downloading the program code to the DSP or the like. Image processing devices using conventional programmable devices such as DSPs or the like, however, are problematic in that the latter require a program memory and a data memory for each process, and hence the scale of the DSPs or the like becomes larger upon execution of plural process functions, as described above, incurring then greater costs than ASICs or the like. Multiplication of image data, moreover, requires data memories with expanded capacity, which inevitably incurs higher costs.